This book constitutes the refereed proceedings of the 4th International XML Database Symposium, XSym 2006, held in conjunction with the International Conference on Very Large Data Bases, VLDB 2006. The book presents 8 revised full papers, focused on building XML repositories and covering query processing, caching, indexing and navigation support, structural matching, temporal XML, and XML updates. Topical sections include query evaluation and temporal XML, XPath and twigs, and XML updates.
Query Evaluation and Temporal XML.- Kappa-Join: Efficient Execution of Existential Quantification in XML Query Languages.- Index vs. Navigation in XPath Evaluation.- Consistency of Temporal XML Documents.- XPath and Twigs.- A Logic-Based Approach to Cache Answerability for XPath Queries.- FLUX: Content and Structure Matching of XPath Queries with Range Predicates.- A Resource Efficient Hybrid Data Structure for Twig Queries.- XML Updates.- On the Expressive Power of XQuery-Based Update Languages.- Efficient Incremental Validation of XML Documents After Composite Updates.